Spot prevention in light-sensitive silver halide emulsion layers



United States Patent SPOT PREVENTIGN IN LIGHT-SENSITIVE SILVER 7 many No Drawing. Filed Aug. 10, 1964, Ser. No. 388,669

Claims priority, application Germany, Aug 24, 1963, A 43 8 6 Claims. (or. 9694) This invention relate to improved photographic mate rials comprising at least one light-sensitive silver halide emulsion layer which material has added thereto special compounds capable of reducing or inhibiting the formation of spots or stains in the processed silver halide emulsion layer, due to the presence of dust particles of metals or metal compounds.

The manufacture and processing of photographic material should be effected With complete exclusion of dust. Consequently, provision is made in the art to free the drying air from dust particles by filtration. Despite precautionary measures, however, it is not possible completely to prevent dust particles being deposited, more especially during the manufacture of the photographic material, and these particles become visible as dark or light spots on the processed photographic material, depending upon whether their action is sensitizing or desensitizing.

Particularly fine particles of metals or metal compounds especially oxides, for example, of iron, aluminium, chromium, nickel or copper, are very disturbing in this respect. Various types of additives have been proposed in the literature'to prevent such disturbances. For example, British Patent 623,448 describes aldoximes, which are added to the developer solution or the emulsion in order to take up copper ions. It is further described to utilize acyloins, alkali metal pyrophosphates, metaphosphates, tripolyphosphates and hexametaphosphates, alkali metal oxalates, tartrates,,silicates, carbonates and bicarbonates, tungstates, rhenates, os-mates, molybdates, chromate and derivatives of ethylene diamine tetracetic acid for restricting the spot or stain formation due to dust particle's.

The above compounds are, however, of limited utility since they are either effective only with certain emulsions or since they deleteriously affect photographic or mechanical properties of the photographic material.

It is therefore an object of the present invention to provide antistain agents which have no deleterious effect on photographic materials and which prevent the formation of stain or specks due to the action of dust particles.

A further object is to provide photographic silver halide emulsion layer containing those antistain agents. Other objects will appear from the following description of our invention.

The above objects are accomplished by adding to a silver halide emulsion layer of a photographic material a derivative of o-hydroxybenzylamine, the amino group of which is substituted by 2 alkyl radicals containing car,- boxy groups. The carboxyl substituted alkyl radical having preferably up to carbon atoms.

Particular utility is exhibited by compounds embraced by the following formula:

3,312,552 Patented Apr. 4, 1967 "ice wherein X and Y each represent hydrogen, halogen such as chlorine or bromine, an alkyl radical, preferably up to 3 carbon atoms such as methyl, ethyl or propyl, a nitro group or a snlphonic acid group, an alkoxy radical having preferably up to 3 carbon atoms, such as methoxy or ethoxy, carboxyl, or the radical Z stands for hydrogen, halogen such as chlorine or bromine, an alkyl radical, preferably up to 3 carbon atoms such as methyl, ethyl or propyl, a nitro group or a sulphonic acid group, an alkoxy radical having preferably up to 3 carbon atoms, such as 'methoxy, ethoxy or carboxyl;

R and R each represent a carboxyalkyl radical preferably having up to 5 carbon atoms, or salt of the said carboxyalkyl radical.

The compounds according to the invention are added to the photographic emulsions in quantities from 0.1 g. to 15 g. per mol of silver :halide. The compounds are preferably added as an aqueous solution of their alkali salts to the photographic emulsions Which are ready for casting.

Suitable compounds are, for example:

HO 0 o-oHt t CHZ-GOOII NCH2 CI'IPN no 0 o-orn C1'I2 COOH (II) OH rrooo-oI-n CHCOOH NCH2 CHr-N HO 0 o-om orn-ooorr (III) OH HO 0 o-orn l CH2-COOI1 NCHz CHz-N HO 0 o-om CHz-COOH l on,

' (IV) OH CHr-COOH H3CO OI'I2 N GHr-COOH '(v on Ont-coon o1- orig-N CHrCO0H The compounds used according to the invention can be prepared by known processes, for example, as described in Helv. Chim. Acta, 1952, 35, 1785-93, and CA, 1954, 48, 6722.

By way of example, Compound IV is obtained as a sodium salt by reacting o-vanillin with glycine, hydrogenating the Schiffs base which is formed with R-aney nickel and reacting the product with sodium chloroacetate.

Compound V1 is obtained as a sodium salt by reacting 2-hydroxy-5-nitr-obenzylchloride with aminobutyric acid and reacting the product with sodium chloroacetate.

The antistain agents of the present'invention are prefer-a'bly added to the silver halide emulsion. They can, however, also be added to other layers of the photographic elements, such as protective layers, filter layers, antihalation layers and baryta coatings.

The present invention is not restricted to any special silver halide emulsions. The silver halide may consist of silver chloride, silver bromide, silver iodide or mixtures thereof. The emulsions can be optically or chemically sensitized according to any accepted manner. The emulsions may further contain color coupler, stabilizers, coating aids and other additives, which are commonly usedin the art.

The following example serve to illustrate the present invention.

Example 1 p-Methylaminophenol IHydroquinone .P-otassium metabisulfite Sodium sulfite (anhydrous) Sodium carbonate (anhydrous) Potassium bromide Sodium metaphosphate 4.0 Disodium salt of ethylene diamine tetra-acetic acid" 0.2 Water to make one liter.

The dust particles cause the formation of black spots surrounded by halos on the processed photographic element. The results are given in the following table:

TABLE 1 Relative Sample Addenda per kg. of emulsion number of black stains A Standard B 3 ml. of a 25% aqueous solution of the disodium salt of Compound VII. 0 C s. 5 ml. of a 25% aqueous solution of the disodium 2U salt of ethylenediainine tetraacetic acid. D 10 ml. of a 10% aqueous solution of the sodium 70 salt of 2-hydroxy-5sulfo benzoic acid. E 200 ml. of a 2% aqueous solution of the sodium El) salt of 2-liydroxy-heuzylainino acetic acid.

Example 2 An ordinary photographic silver bromide emulsion which contains 42 g. silver bromide per kg. of emulsion is divided into several portions. Various antistain agents were then added in solution in water in the amounts indicated in the following table. The various portions of the emulsions were then coated at pH 7 on a supported gelatin layer containing dust particles of iron (fine partices of ferrum reductum). The dried coatings were then exposed and developed for about 5 minutes in the photographic developer described in Example 1.

The dust particles cause the formation of black spots surrounded by halos on the processed photographic element. The results are given in the following table:

TABLE 2 Relative Sample Addenda per kg. of emulsion number of black stains A Standard. 100 B. 0.7 g. ofthe sodium salt of Compound I (dissolved O in 5 ml. of water). C 0.7 g. 01 the sodium salt of Compound VII (dis- 0 solved in 3 ml. of water).

Example 3 An ordinary photographic silver bromide emulsion which contains 63 g. of silver bromide per kg. of emulsion is divided into several portions. Various antistain agents were then added in solution in water in the amounts indicated in the following table. The various portions of the emulsions were then coated at pH 5.8-5.9 on a supported gelatin layer containing dust particles of iron (fine particles of ferrum reductum). The dried coatings were then exposed in the photographic developer composition described in Example 1-.

The dust particles cause the formation of black spots surrounded by halos on the processed photographic element. The results are given in the following table:

TABLE 3 Relative Sample Addenda per kg. of emulsion number of black stains Standard 100 7 ml. of a 10% aqueous solution of the sodium 0 salt of Compound VII.

Example 4 An ordinary photographic silver bromide emulsion which contains 83 g. silver bromide per kg. of emulsion is divided into several portions. Various antistain agents were then added in solution in water in the amounts indicated in the following table. The various portions of the emulsions were then coated at .pH 6.5 on a supported TABLE 4 Relative number of black stains Sample Addenda per kg. of emulsion Standard 0.5 g. of sodium salt of ethylenediamiue tetraaeetic acid (dissolved in 20 m1v of water).

0.5 g. of Compound VII Example 2 silver bromide emulsions, the one containing 80 g. of silver bromide per kg. of emulsion and the other 130 g. of silver bromide per kg. of emulsion are divided in several portions. Various antistain agents are added in solution in water in the amounts indicated in the following table. The various portions of the emulsions are then coated at a pH of 6.7 each on 1 side of a transparent transport of cellulose acetate which is coated on each side with a gelatin layer containing fine particles of rust and iron. The resulting photographic material is processed as described in Example 1.

The results of the comparison tests are given in the following table:

TABLE 5 Relative number of black stains Sample Addenda per kg. of emulsion Standard 0.5 g. of the sodium salt of ethylenediamine tetraacetic acid.

0.5 g. of Compound VII 0 6 wherein R and R each represent a carboxyalkyl radical having up to 5 carbon atoms;

X and Y each represent a member of the group consisting of hydrogen, halogen, alkyl, nitro, sulfo, alkoxy, carboxyl and a radical of the following formula Z stands for a substituent of the group consisting of hydrogen, halogen, alkyl, nitro, sulfo, alkoxy, ethoxy and carboxyl.

3. A photographic material as defined in claim 2, containing as an antistain agent an effective amount of the following compound:

Hooo0m 1 our-coon NCH2 CH2N nooo om our-coon I SOaH 4. A photographic material as defined in claim 2, containing as an antistain agent an eifective amount of the following compound:

| OI-Ir-OOOH HaC-O OHPN OHzOOOH 5. A photographic material as defined in claim 2, containing as an antistain agent an effective amount of the following compound:

CHzN

OHr-COOH 6. A photographic material as defined in claim 2, con taming as an antistain agent an effective amount of the following compound:

CHz-OOOH No references cited.

NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner. 

1. A PHOTOGRAPHIC MATERIAL CONTAINING AT LEAST ONE SUPPORTED LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER, THE SAID MATERIAL CONTAINS AS AN ANTISTAIN AGENT AN EFFECTIVE AMOUNT OF AN O-HYDROXYBENZYLAMINE, THE AMINO GROUP OF WHICH IS SUBSTITUTED BY 2 ALKYL RADICALS CONTAINING CARBOXYL GROUPS. 